The smooth bearings of an internal combustion engine are lubricated by oil under conditions of pressure, of temperature, of grain size of possible impurities, and of water content on admission to the engine that are all monitored in operation.
Untimely deterioration in one or more of these parameters can cause the film of oil that normally separates the bearing from its bush to disappear. The resulting metal-on-metal contact at the conditions of relative speed and of unit pressure existing in the engine then gives rise to the metal of the bearing and of the bush becoming welded together locally and this gives rise to permanent damage of the bearing called "seizing" after some variable length of time that depends on the extent to which the oil film is reduced.
Various apparatuses are already known for warning the driver of the engine that seizing phenomena are beginning. The bush or its immediate environment may be fitted with a temperature sensor, but this can be difficult for a big-end bearing. A sudden and rapid rise in the temperature of the bush represents abnormal heating of the parts in frictional contact, and a priori the cause of such a temperature rise will be seizing.
The drawback of such apparatuses for monitoring the bearings in an internal combustion engine lies in the fact that they are not preventative since seizing must have begun before it can be detected. They are intended merely for reducing the amount of damage that occurs by enabling the driver of the engine to respond quickly.
According to the present invention, proposals are made to remedy this problem by means of a device that provides genuinely preventative detection of seizure conditions in the bearings of a reciprocating machine, and in particular the bearings of an internal combustion engine.